Land Contamination Risk Assessments

Landowners faced with land contamination have two options: either undertake further site data collection and risk assessments, or remediate the soil and/or groundwater. A generic quantitative risk assessment (DQRA) involves detailed risk assessments that analyse site-specific factors and, where applicable, the attenuation of contaminants in the environment such as by dilution and degradation. A DQRA aims to find out more about the potential environmental liabilities or risks posed by contaminant sources at a specific site and enables a move from conservative remedial targets or assessment criteria based on generic assumptions to site-specific remedial targets or assessment criteria that are usually less conservative.


Group-wide excellence

RSK’s Geosciences team has a UK-leading land contamination risk assessment capability through specialists in DQRAs for human health, controlled waters, the water environment, asbestos, ground gas and vapours, non-aqueous phase liquids (NAPL) and other technical areas. Many of our risk assessors are SiLC and Society of Brownfield Risk Assessment (SoBRA) accredited. We contribute to initiatives led by SoBRA and others to develop industry practices in this area.

Our team is experienced in using various risk assessment models, including the Environment Agency’s contaminants in soil and remedial targets methodology for controlled waters, risk-based corrective action, ConSim software and the groundwater spatiotemporal data analysis tool.

Understanding clients; applying decades of experience

For clients seeking a land contamination assessment, commissioning a competent and comprehensive desk study, including a preliminary risk assessment, is the first stage for a successful project. The assessment develops an outline conceptual model that qualitatively evaluates whether there are unacceptable risks to land, water or the wider environment.

The second stage is twofold: a generic quantitative risk assessment (GQRA) and a DQRA. The GQRA uses generic assessment criteria (GAC) and associated assumptions, alongside data from a phase 2 intrusive investigation, which evaluates the potential risks to receptors identified in the phase 1 assessment.

For almost 35 years, RSK has been assisting its clients by providing GQRAs and DQRAs that determine and define the current or future potential liabilities and risks associated with a site, thereby guiding clients through the planning process and supporting them in due diligence work.

Adept teams offering invaluable services

Our specialised quantitative risk assessment team provides detailed site conceptualisations and GQRAs and DQRAs relating to human health, vapour intrusion into buildings, ground gas and controlled waters (or the water environment in Scotland). Our range of services includes phase 1 reports and preliminary risk assessments; intrusive site investigations and GQRAs; DQRAs for controlled waters and human health; bioaccessibility testing to support a DQRA; the derivation of site-specific assessment criteria and remedial targets for use in a DQRA; fate and transport modelling; NAPL modelling; assessing monitored natural attenuation (MNA); and sustainability appraisals and cost–benefit analyses.



DQRA benefits

Soil and groundwater remediation, although designed to reduce or remove contamination to levels that do not pose unacceptable risks to receptors, has the potential to cause environmental, economic and social impacts. Therefore, completing a DQRA to understand the site circumstances better may negate the need for such an intervention. Typically, the long-term financial savings through less need to remediate a site usually vastly offset the cost of gathering and processing more data as part of a DQRA while still ensuring the site does not pose a risk to receptors. An added benefit of carrying out a DQRA is the sustainability of reusing or retaining soils on-site. For example, in some cases, it can be more environmentally sustainable, as there is less impact on local air quality, less fuel used and less use of landfill capacity, as well as being potentially more cost-effective to treat material on-site than to transport it for off-site disposal.

Connecting with clients

RSK’s specialist technical staff are experienced geoenvironmental consultants and leaders in site investigation, quantitative risk assessment and remediation. This experience and knowledge are instrumental in providing comprehensive human health and controlled waters risk assessments; gaining regulatory consent through the planning or environmental permitting regimes; attending court; and providing expert witness testimony if required.

RSK can offer remedial options appraisal, including sustainability appraisals, remediation method statements and remediation strategies, and verification reports in accordance with current guidance, standards and legislation.

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Our Expertise

  • Human health risk assessments

    Our specialists undertake soil assessments using in-house GAC for assessing the risks from soil-borne contaminants. Our vapour assessments assess the risks from volatile contaminants in groundwater and from indoor inhalation exposure. DQRAs undertaken for human health use current UK and international models and software, as appropriate to the site circumstances, the identified pollutant linkages and the current or future land use. RSK can also offer quantitative risk assessments relating to the risks associated with asbestos in soil.

  • Controlled waters risk assessments

    RSK can offer GQRAs or DQRAs for controlled waters (the water environment in Scotland) relating to surface water, groundwater, drinking water supplies and sustainable drainage systems (SuDS), and in relation to environmental permit discharge consents. Through deriving remedial targets based on data collected during an intrusive investigation, we can advise clients of their potential liabilities, if DQRA is required and what its benefits would be, and develop the most appropriate remedial strategy for a site. Our specialists can also assess sites with NAPL contamination and develop appropriate remediation methods.

  • Ground gas and soil vapour risk assessments

    Using their extensive expertise, our specialists can develop site-specific ground gas conceptual models, undertake generic ground gas risk assessments and gas generation and migration modelling, and complete DQRAs for ground gas. We also have specialist expertise in soil vapour intrusion (VI) assessments for the petroleum and other sectors.

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